How does one make random number between range for

Question

so my goal in this codebit is to randomly roll two dice and as we all know your regular die only has 6 sides so I imported Foundation for access to arc4random_uniform(UInt32). I attempted using the range of (1..7) to avoid randomly getting 0 however that returned an error which I didn't enjoy too much. I tried to do this:

dice1 = arc4random_uniform(UInt32(1..7))

however that returned

Could not find an overload for 'init' that accepts the supplied arguments

I hope that this is enough information for you amazing debs out there to help me :)

Please note I am just doing this in a playground to practice swift. It isn't imperative that I learn how to do this; it's just me tinkering before I jump into building actual apps :D

//imports random number function
import Foundation
//creates data storage for dice roll
var dice1: UInt32 = 0
var dice2: UInt32 = 0
//counter variable
var i = 0
//how many times snake eyes happens
var snakeeyes = 0
 //how many times a double is rolled
var `double` = 0
//rolls dice 100 times
while i < 100{
    //from here
    //sets dice roll

This returns an error of 'Range $T3' is not convertible to UInt32

   dice1 = arc4random_uniform(1..7)
   dice2 = arc4random_uniform(1..7)

    //checks for snake eyes
    if dice1 == 1 && dice2 == 1 {
        snakeeyes = snakeeyes + 1

    }
    //checks for doubles
    if dice1 == dice2{
        `double` = `double` + 1
    }
    //increases counter
        i = i + 1
    //to here
}
println("You got Snake Eyes \(snakeeyes) times.")
println("You got Doubles, \(`double`) times.")

Answer 1

var rangeFromLimits = arc4random_uniform( (UPPerBound - LOWerBound) + 1)) + LOWerBound;

Answer 2

According to Swift 4.2 now it's easily to get random number like this

let randomDouble = Double.random(in: -7.9...12.8)

let randomIntFrom0To10 = Int.random(in: 0 ..< 10)

for more details check this out

Answer 3

Not sure why nobody else here extends Range:

public extension Range where Bound == Int {
    var random: Int {
        return lowerBound + Int(arc4random_uniform(UInt32(upperBound - lowerBound)))
    }
}

public extension ClosedRange where Bound == Int {
    var random: Int {
        return lowerBound + Int(arc4random_uniform(UInt32(upperBound - lowerBound + 1)))
    }
}

In use:

let foo = (100..<600).random

Answer 4

Since Swift 4.2:

Int {    
    public static func random(in range: ClosedRange<Int>) -> Int
    public static func random(in range: Range<Int>) -> Int
}

Used like:

Int.random(in: 2...10)

Answer 5

Swift 3 Xcode Beta 5 Solution. Based on Ted van Gaalen Answer.

extension Int
  {
     static func random(range: Range<Int> ) -> Int
    {
        var offset = 0

        if range.lowerBound < 0   // allow negative ranges
        {
            offset = Swift.abs(range.lowerBound)
        }

        let mini = UInt32(range.lowerBound + offset)
        let maxi = UInt32(range.upperBound   + offset)

        return Int(mini + arc4random_uniform(maxi - mini)) - offset
    }
}

Answer 6

Probably one find useful this a bit updated version of Range extension from Ted van Gaalen's answer using Swift 4/Xcode 9+:

extension CountableClosedRange where Bound == Int {
    var randomFromRange: Bound {
        get {
            var offset = 0
            if lowerBound < 0 {
                offset = abs(lowerBound)
            }
            let mini = UInt32(lowerBound + offset)
            let maxi = UInt32(upperBound + offset)
            return Int(mini + arc4random_uniform(maxi - mini)) - offset
        }
    }
}

let n = (-1000 ... 1000).randomFromRange
print(n)

Or this a bit "hacky" solution to support open and closed intervals:

extension CountableRange where Bound == Int {
    var randomFromRange: Bound {
        return uniformRandom(from: lowerBound, to: upperBound)
    }
}

extension CountableClosedRange where Bound == Int {
    var randomFromRange: Bound {
        return uniformRandom(from: lowerBound, to: upperBound - 1)
    }
}

func uniformRandom(from: Int, to: Int) -> Int {
    var offset = 0
    if from < 0 {
        offset = abs(from)
    }
    let mini = UInt32(from + offset)
    let maxi = UInt32(to + offset)
    return Int(mini + arc4random_uniform(maxi - mini)) - offset
}

Not sure if there is a way to add property to both types of intervals simultaneously.